Projection screen



May l2, 1942. D. ENEWMAN l 2,282,875

PROJECTION scREN Filed April 1:', 1938 ,y @iM \\\\\\\\\\\\\\\\\\\\\\\\\\vA\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\y\\\\\\\\\\\\\ INVENTOR 0pm, @M4

ATTORN Y 'zontal plane.

atented May 12, 1942l azsizsm e T OFFICE raoiaorron sonnen David F. Newman, Rockville Centre, N. Y., as-

signor to Trans-Lux Corporation, New York, N. Y., a corporationof Delaware l l Application April 13, 1933, Serial No. 201,670

(ci. ias-zii 2 Claims.

My invention relates to a projection screen.

In accordance with my invention, a sheet of fabric and a layer of comminuted material are disposed closely adjacent each other at one side of a sheet-like body of translucent material so as to form an efficient, practical screen of the rear projection type.

Various other objects, advantages and characteristics of my invention will become apparent from the following detailed description.

My invention resides in the projection screen, features and arrangements. of the character hereinafter described and claimed. K

- For an understanding ofmy invention and for an illustration of one form thereof, reference is to be had to the accompanying drawing, in which:

Figure 1 is a vertical sectional view showing a showing a molding table having viscous screenforming material disposed thereon;

Figs. 3, 4 and 5 are vertical'sectional views illustrating progressive stages of the screen-forming method: and

Fig. 6 is an enlarged vertical sectional view showings. section of my novel projection screen.

Referring to Figs. 2, 3, 4 and 5, T diagrammatically illustrates the glasstop, or equivalent, of a molding table which,'as well understood in the art, may be supported by table legs, not shown. A table top T of th'e character thus described is usually of square or rectangular oonguration and, as indicated, each side thereof has secured thereto an upstanding strip-like member 2. As shown on the drawing, the upper surface of the table top T is of plane configuration and said upper surface should coincide with a horiequal height throughout the length thereof so that the upper surface of said members 2 like- `rial M which should be of such character that the completed screen has the desired degree of translucency. Any suitable screen-forming material may thus be utilized such, for example, as

disclosed in U. S. Letters Patent Nos. 1,151,502 and 1,881,128. If the screen-forming material M is to be of the character just stated,'it may comprise suitably proportioned amounts of gelatine, 55 said .fabric sheet S. In this manner, said fabric Further, the members 2 are oi glycerine and water with .which there may be combined or associated one or more agents imparting a desired characteristic or characteristics to the completed screen. Thus, there may be incorporated in the screen-forming material lose-acetate in the manner disclosed and claimedl in U.' S. Patent No. 2,024,382.

After the aforesaid mass of screen-forming material M, While viscous, has been deposited on the upper surfaceof the table top T as shown in Fig. 2, it should be brought to substantially the thickness which the completed screen is to have. This operation may be performed as indicated in Fig. 3 wherein a. straightedge d is shown as occupying the position which it takes when it is moved horizontally above the table top T with the lower edge thereof in engagement with the upper surfaces of the members 2. the foregoing, it will be understood that, by the use of the. straight edge t, the viscous screenforming material M is so shaped that it forms a sheet-like translucent body B utilizable for projection 'screen purposes as hereinafter described. As stated above, the table top T is preferably square or rectangular. Adapted for association with said table top T is a frame F, Figs. 1, 4 and 5, which conforms in configuration substantially with that of-said table top T althoughenclosing a. somewhat greater area. In accordance with the invention, the frame F is adapted to have a suitable fabric sheet S secured thereto in suitable taut condition-as shown in Fig. 1. For thus securing the fabric sheet S to the frame F, there may be utilized tacks 6, or equivalent. The fabric sheet S may be of any suitable character such, for example, as georgette crepe, knit fabric, net fabric, or the like.

. with the fabric sheets secured to the frame F l, as shown in Fig. 1, the combined frame and sheet may be associated with the table top T and the sheet-like translucent body B disposed thereon, Fig. 4. In so doing, said fabric sheet S, which preferably is slightly greater in area than-that of the table top T, comes to rest upon the aforesaid sheet-like translucent body, the frame F being suspended in'space'and supported solely by In View of the fabric sheet S sinks into or becomes incorporated in said sheet-like translucent body B.

In accordance with an important phase of my invention, suitable comminuted light-diffusing material, as finely divided glass, is applied to the upper surface of the partially completed screen as it rests upon the table top 'I'. Such light-diffusing material is advantageously applied to the screen surface by an air gun or in suitable manner whereby a layer L thereof is formed on the upperscreen surface closely adjacent the aforesaid fabric sheet S. After the upper surface of the screen has been suitably covered by the aforesaid light-diffusing material and after the proper time interval has elapsed, any excess or non-adhering material may be brushed or blown away whereby the upper screen surface retains only a relatively thin coating of said light-diffusing material. l

Prior to the time that the aforesaid mass of screen-forming material M was placed on the table top T, it had been heated and, therefore, was kmore or less viscous. In accordance with standard practice, said table topi T is maintained at elevated temperature by suitable means, not shown, so that the heat is not rapidly disseminated from the screen-forming material. Accordingly., it follows that the screen-forming material, after it has been brought to sheet-like formation and during the application thereto of the fabric sheet F and the comminuted material, remains semi-viscous, or more or less tacky.

-As a result, the fabric sheet S readily becomes amalgamated with the upper surface of the sheetlike translucent body B. Likewise, by the `adhesive action of said translucent body, the aforesaid comminuted material becomes attached or secured to said sheet-like translucent body B directly above the fabric sheet S.

After the operations described above have been completed, the lheating means for the molding table is deenergized and said table together with the screen structure thereon is allowed to cool. Thereafter, a knife may be passed around the table on the inside of the members 2 whereupon the screen may be removed from the table top T and the edges thereof suitably bound so that frame and used as a part of a rear projection system.

forming material which includes a desired quantity of 'a light-diffusing agent or such light-diffusing agent may be entirely omitted when screens having a high light-transmission factor are desired. Thus, a selected quantity of the light-diffusing agent may be utilized and, even so, particularly by reason of the coating of comminuted material, the completed screen invariably performs in a highly satisfactory manner for the intended purpose. v

With a screen of the character herein described, the sheet of fabric and the comminuted material are concentrated substantially in a single plane at one side of the screen. Preferably, the objective lens of the projecting system is focussed on this plane and, hence, particularly with short focal length objective lenses, there is less loss of light than would occur if the diffusive material was distributed throughout the thickness of the screen.

While the invention has been described with respect to a certain particular preferred example which gives satisfactory results, it will be said screen may be secured within a suitable understood by those skilled in the art after understanding the invention, that various changes and modifications may be made without departing from the spirit and scope of the invention and it is intended therefore in the appended claims to cover all such changes and modifications.

What is claimed as new and desired to be secured by Letters Patent is:

1. A projection screen comprising a sheet-like translucent body, and a plurality of layers of light-diffusing material adhering to said translucent body, one of said layers being a fabric sheet and another of said layers being formed from comminuted material, said fabric sheet and said layer of comminuted material being disposed on the same side of said translucent body and said layer of comminuted material overlying said fabric sheet.

2. A projection screen comprising a sheet-like translucent body, and a plurality of layers of light-diffusing material associated with said translucent body, one of said layers being a fabric lsheet adhering to said translucent body and another of said layers being formed from comminuted material, said fabric sheet and said layer of Acomminuted material being disposed on lthe same side of said translucent body and said layer of comminuted material 4overlying said fabric sheet, the comminuted material being secured to the translucent body by the adhesive action of said translucent body.

DAVID F. NEWMAN. 

